The Peace Corps began in 1961 under President Kennedy as a way to promote peace and understanding between countries. Since then volunteers have served in developing countries all over the world. Today volunteers work in 6 different fields: education, health, environment, community and economic development, and agriculture. As of 2009 the Peace Corps is in 68 countries around the world.
To learn more about the program in Thailand: http://thailand.peacecorps.gov